Re: [PATCH] Fix ICE in ssa_create_duplicates (PR tree-optimization/90671)

[Richard Biener <rguenther@suse.de>]

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On Thu, 30 May 2019, Jakub Jelinek wrote:

> Hi!
> 
> The following testcase ICEs on the trunk, because both gsi_split_seq_after
> and gsi_insert_seq_after have assertions that the split is not after
> gsi_end_p iterator or insertion is not after such an iterator.
> 
> My understanding of Alex' change is that it wants to hide any added
> debug stmts temporarily from create_block_for_threading duplication, so that
> it remains just in one of the blocks.  Now, template_last_to_copy is
> initialized using last_bb (template_block), if that block is initially
> completely empty, template_last_to_copy will be gsi_end_p, gsi_stmt on it
> NULL, so I think in that case we can't split any sequence anywhere, we
> simply want to hide the whole sequence from the block duplication and put it
> in afterwards.
> 
> The following patch does that.  Bootstrapped/regtested on x86_64-linux and
> i686-linux, ok for trunk?

OK.

Richard.
 
> 2019-05-30  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR tree-optimization/90671
> 	* tree-ssa-threadupdate.c (ssa_create_duplicates): If
> 	template_block used to be empty on the first call, don't use
> 	gsi_split_seq_after and gsi_insert_seq_after, but remember whole
> 	seq with bb_seq and set it with set_bb_seq.
> 
> 	* gcc.dg/torture/pr90671.c: New test.
> 
> --- gcc/tree-ssa-threadupdate.c.jj	2019-05-23 12:57:15.522512319 +0200
> +++ gcc/tree-ssa-threadupdate.c	2019-05-30 10:15:44.718468219 +0200
> @@ -1142,12 +1142,25 @@ ssa_create_duplicates (struct redirectio
>        gimple_seq seq = NULL;
>        if (gsi_stmt (local_info->template_last_to_copy)
>  	  != gsi_stmt (gsi_last_bb (local_info->template_block)))
> -	seq = gsi_split_seq_after (local_info->template_last_to_copy);
> +	{
> +	  if (gsi_end_p (local_info->template_last_to_copy))
> +	    {
> +	      seq = bb_seq (local_info->template_block);
> +	      set_bb_seq (local_info->template_block, NULL);
> +	    }
> +	  else
> +	    seq = gsi_split_seq_after (local_info->template_last_to_copy);
> +	}
>        create_block_for_threading (local_info->template_block, rd, 0,
>  				  &local_info->duplicate_blocks);
>        if (seq)
> -	gsi_insert_seq_after (&local_info->template_last_to_copy,
> -			      seq, GSI_SAME_STMT);
> +	{
> +	  if (gsi_end_p (local_info->template_last_to_copy))
> +	    set_bb_seq (local_info->template_block, seq);
> +	  else
> +	    gsi_insert_seq_after (&local_info->template_last_to_copy,
> +				  seq, GSI_SAME_STMT);
> +	}
>  
>        /* Go ahead and wire up outgoing edges and update PHIs for the duplicate
>  	 block.   */
> --- gcc/testsuite/gcc.dg/torture/pr90671.c.jj	2019-05-30 10:20:13.686068207 +0200
> +++ gcc/testsuite/gcc.dg/torture/pr90671.c	2019-05-30 10:19:50.815442342 +0200
> @@ -0,0 +1,16 @@
> +/* PR tree-optimization/90671 */
> +/* { dg-do compile } */
> +/* { dg-additional-options "-w -g" } */
> +
> +int a;
> +
> +int
> +main ()
> +{
> +  int b, c;
> +  for (c = 0; c < 2; c++)
> +    while (a)
> +      if (b)
> +	break;
> +  return 0;
> +}
> 
> 	Jakub
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany;
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